As a conventional injection nozzle, there is known one made up of an inner cylinder which is shaped like a syringe needle having formed a discharge port at a front end thereof, and an outer cylinder which slidably supports the inner cylinder around its inner circumference, and the inside of which serves as a passage for an adhesive. The inner cylinder advances relative to the outer cylinder upon receiving an injection pressure of the adhesive (see JP-A 2003-147971). In a pinning method using this injection nozzle, after boring a charging hole into a portion requiring repairs on an outer wall which is made up of a finishing material (tile, stone, and the like), mortar, and concrete framework, injection of the adhesive (epoxy resin adhesive) is performed by using a resin injector (i.e., an injector for injecting a resin) having the injection nozzle mounted thereon. Specifically, the injection nozzle is held while urged against an opening portion of the charging hole, and the resin injector is pumped. Then, the inner cylinder advances first upon receipt of a charging force by the adhesive, and a discharge port of the inner cylinder reaches the bottom of the charging hole. Thereafter, the adhesive starts being discharged out of the discharge port, whereby the adhesive is gradually filled from the deepest portion of the charging hole.
With this kind of conventional injection nozzle, it is possible to fill the charging hole with the adhesive starting with the deepest portion thereof. Therefore, there is no possibility that air accumulation or the like occurs in the deepest portion of the charging hole. However, if the clearance (so-called “separated portion”) between the mortar and the concrete framework is large, the adhesive is likely to flow into the clearance, thereby resulting in a possibility that the adhesive does not reach a shallow position of the charging hole. Particularly, in case there has also occurred a “separated portion” between the finishing material and the mortar, it is not possible with the above-described method to sufficiently fill the “separated portion” with the adhesive. As a solution, it becomes necessary to perform the injection work while pulling out the injection nozzle down to the “separated portion.” In this case, however, since the sealing of the opening portion of the charging hole is released, it becomes impossible to sufficiently inject the adhesive into this kind of portion.